I suggest breaking the revision down a bit. List the topics. Take them one at a time. For each do the following: learn a set of key FACTS regarding it.... such as crime stats, examples with dates etc. This is the evidence based stuff you will need for the essays. Learn these using memory techniques such as making up words that begin with the starting letter of each fact to prompt your recall. Sometimes it works to visual a picture that sums the fact up for you... such as a person wearing clothes relevant to the dates you are trying to remember or standing in the place you need to know and holding up a sign with the key fact or facts on it. Then you recall the picture to access all the points you needs. If you are a verbal learner get someone to ask you to repeat the facts to them. Some people make lists or write out the facts over and over. Anything that works for you.
Thats the bit that needs to get into your memory system.
The other part is the concepts and ideas. This is easy peasy if you've understood them clearly in the first place as its a case of listing them out in a shortened version and making sure you have some facts and examples in your head to go with them. If though at this point you are still struggling with some ideas and concepts then take a deep breath. Sit down and try to break the ideas you are struggling with into much smaller parts and working through them a small piece at a time. Again if you are a verbal learner then try explaining the ideas out loud to someone and you'll either realise you don't have clue or that it is all actually getting clearer as you explain. If you don't have a clue then revise that bit over again, ask your tutor to explain it, read it, ask someone to ask you questions such as 'what does that mean?' and if you don't know the answer look it up there and then and tell them. Other techniques are to pretend you are doing a talk on a particular subject, arrange the points on a piece of paper and act out the 'speech' to an imaginary audience. You'll spot bits on which you are weak. If you're visual by nature try mind-mapping out the ideas with pictures etc. Close your eyes and try to remember what it all looks like. If you're systematic then make lists and count up the number of points you'd need to make about that topic. ie there are five points to make about ethnicity and crime. I have two examples per point. The five points demonstrate two different ways of looking at the issue etc. You memorise the numbers and in the exam whan a question comes up you can recall 'I need five points here' etc.
The whole secret of revision is to break things into small units which you can learn more easily than huge chunks and to use techniques that get things into your head. By the time you've learnt lots of the small units then you've understood and memorised a massive amount that would have been much too big and overwhelming to even think about at the beginning.
Good luck everyone!